|Publication number||US7406946 B1|
|Application number||US 11/695,195|
|Publication date||Aug 5, 2008|
|Filing date||Apr 2, 2007|
|Priority date||Apr 2, 2007|
|Also published as||EP1978240A2, EP1978240A3, EP1978240B1, EP2333305A2, EP2333305A3, USRE43864|
|Publication number||11695195, 695195, US 7406946 B1, US 7406946B1, US-B1-7406946, US7406946 B1, US7406946B1|
|Inventors||Atsushi Watanabe, Harsha Badarinarayan, Jonathan Borg, Donald J. McCune, Takuya Shiraishi, Atsushi Hohkita, Masahiro Soma, Hiroaki Saeki|
|Original Assignee||Hitachi, Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (53), Referenced by (38), Classifications (18), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
I. Field of the Invention
The present invention relates to a method and apparatus for attenuating noise resulting from fuel pump pulsation in a direct injection internal combustion engine.
II. Description of Related Art
Direct injection internal combustion engines have enjoyed increased acceptance for a variety of reasons. In particular, direct fuel injection into the engine combustion chamber typically results in better fuel economy and more efficient operation of the internal combustion engine.
In a direct injection internal combustion engine, a passageway is formed in the engine block, which includes the engine cylinder head, that is open to each combustion chamber. A direct injection fuel injector is then positioned within this passageway for each of the engine combustion chambers so that an outlet from the fuel injector is open to its associated combustion chamber.
Each fuel injector also includes an inlet that is connected by a fuel rail and typically a fuel pipe to a fuel pump. The fuel pump creates high pressure in the fuel rail and this high pressure, in turn, is fluidly connected to each fuel injector. Thus, upon activation or opening of each fuel injector, the injector injects the fuel directly into the engine combustion chamber.
One disadvantage of these previously known direct fuel injection engines, however, is that the fuel pump is typically cam driven and thus creates fuel pressure pulsations to the fuel rail. These fuel pressure pulsations, furthermore, vary in frequency in dependence upon the engine rpm. These fuel pump pulsations disadvantageously result in vibrations that are transmitted by the fuel injectors to the engine block and create an audible and undesirable noise as well as vibration and possible part fatigue.
The present invention provides an apparatus to attenuate the audible noise and vibration created by the previously known direct injection internal combustion engines.
In one form of the invention, a direct injection fuel nozzle is associated with each engine combustion chamber in the engine block which, as used herein, includes the engine cylinder head. Each direct injection fuel nozzle, furthermore, is elongated and includes a main body with a fuel inlet at one end and a tip with a fuel outlet at its other end.
An injector cup is secured to the fuel rail which, in turn, is fluidly connected to the fuel pump. Each injector cup, furthermore, includes an open end cavity with the fuel rail and is dimensioned to receive a portion of the main body of the fuel injector. This portion of the fuel injector, furthermore, is fluidly sealed to the injector cup by an O-ring or similar seal.
An injector holder assembly then secures the fuel injector to the injector cup so that the fuel injector is suspended from the fuel rail. Simultaneously, the injector tip of the fuel injector is positioned within the engine block passageway open to the combustion chamber. However, the injector holder assembly maintains the injector tip at a position spaced from the walls of the block passageway thus avoiding metal-to-metal contact between the fuel injector and the engine block. The fuel tip is then fluidly sealed to the engine block passageway by a seal which may be non-metallic.
Since the injector holder assembly suspends its associated fuel injector from the fuel rail thus avoiding metal-to-metal contact with the engine block, fuel pressure pulsations that are transmitted to the fuel injector and can cause vibration are effectively isolated from, and thus attenuated by, the seal between the injector tip and the engine block.
In a modification of the invention, the fuel injector is mounted to the injector cup so that the fuel injector may pivot or swivel slightly relative to the injector cup. Tapered surfaces on the injector reduces the bending arm between the injector and its mounting clip and thus reduces stress.
In still another form of the present invention, the inlet for the fuel injector extends radially outwardly from the fuel injector main body at a position spaced inwardly from its end positioned within the injector cup. A pair of annular seals are then positioned between the injector main body and the injector cup such that the seals create an annular fluid chamber in communication with the injector inlet. This annular chamber in turn is fluidly connected to the fuel rail.
Consequently, during operation of the fuel rail, the high pressure within the fuel rail simultaneously imposes a force on both O-rings that are substantially equal in magnitude, but opposite in direction. As such, fuel pressure on the fuel injector in a direction towards the injector tip that would otherwise occur, together with vibrations resulting from that axial force, is avoided.
In still another form of the invention, an enlarged diameter reservoir is fluidly provided in series between the fuel pump and the fuel injectors. In one embodiment, a fuel pipe fluidly connects the fuel pump to one or more fuel rails. A reservoir is then positioned fluidly in series in the fuel pipe immediately upstream from the fuel rail. In practice, the reservoir functions to dampen and attenuate vibrations from the fuel pump before such vibrations reach the fuel rails.
In another form of the invention, the reservoir is positioned between the fuel rails and each of the fuel injectors. Such fuel reservoirs also serve to dampen the fuel pressure pulsations from the fuel pump.
In yet another form of the invention, a small diameter orifice is provided between the fuel rail and each fuel injector. These small diameter orifices also act to dampen the fuel pressure fluctuations, and thus transmission of vibration from the fuel pump and to the fuel injectors.
A better understanding of the present invention will be had upon reference to the following detailed description when read in conjunction with the accompany drawing, wherein like reference characters refer to like parts throughout the several views, and in which:
With reference first to
A spark plug 23 initiates the fuel combustion in the combustion chamber 26 to drive a piston 25 reciprocally mounted in a cylinder 27 in the engine block 24. Following fuel combustion, the combustion products are exhausted through an exhaust manifold 29.
A direct injection fuel injector 28 is associated with each combustion chamber 26. Each fuel injector 28, furthermore, includes a portion mounted within a passageway 30 formed in the engine block 24 and open to the combustion chamber 26. One fuel injector 28 is associated with each combustion chamber 26.
The fuel injector 28, which will subsequently be described in greater detail, is fluidly connected to a high pressure fuel rail 32. The fuel rail 32, in turn, is fluidly connected by a fuel pipe 34 to a high pressure fuel pump 36.
The high pressure fuel pump 36 typically comprises a cam pump having a cam 38 that is rotatably driven by the engine. Consequently, operation of the pump 36 produces fuel pressure pulsations through the fuel pipe 34, rail 32 and fuel injectors 28 unless otherwise attenuated.
With reference now to
In order to attach the fuel injector 28, the holder assembly 20 includes an injector cup 50 having a housing defining an interior cavity 52 open at one end 54. The other end of the cavity 52 is fluidly connected to the fuel rail 32 by a fuel port 56.
The injector cup cavity 52 is dimensioned to slidably receive a portion of the injector main body 40 through the open end 54 of the cavity 52. An O-ring or other seal 58 then fluidly seals the outer periphery of the fuel injector main body 40 to the inside of the cavity 52 thus forming a fuel inlet chamber 60. Both the injector inlet 46 and the fuel port 56 between the fuel rail 32 and injector cup 50 are open to the fuel inlet chamber 60.
With reference now to
The holder assembly further comprises an injector clip plate 70, best shown in
The clip plate 70 is constructed of a rigid material, such as metal, and includes a cutout 74 designed to fit around a portion of the main body 40 of the fuel injector 28. With the clip plate 70 positioned around the fuel injector 28, the clip plate 70 abuts against an abutment surface 76 on the fuel injector main body 40.
Consequently, in operation, the clip holder 66 secures the clip plate 70 to the injection cup 50 which, in turn, is secured to the fuel rail 32 in any conventional fashion, such as a press fit. The clip plate 70 then supports the abutment surface 76 of the fuel injector 28. In doing so, the holder assembly 20 together with the injector cup 50 suspends the fuel injector 28 from the fuel rail 32.
Referring again particularly to
In order to seal the fuel tip 42 to the fuel injector passageway 30, a tip seal 78 is provided around the fuel tip 42 such that the tip seal 78 extends between and seals the fuel tip 42 to the passageway 30. The tip seal 78 is constructed of a non-metallic material, such as Teflon. Furthermore, the tip seal 78 may be more axially elongated than that shown in the drawing and, optionally, two or more tip seals 78 may be used with each injector 20.
In operation, since metal-to-metal contact between the fuel injector 28 and the engine block 24 is avoided, the transmission of vibrations or pulsations from the fuel pump to the engine block 24 is likewise avoided.
With reference now to
The tapered surfaces 76′ and 77 on the injector 28 thus allow the injector 28 to swivel or pivot slightly, as shown in
With reference now to
A pair of axially spaced seals or O-rings 80 are then disposed around the main body 40 of the fuel injector 28 such that the O-rings 80 form an annular fuel inlet chamber 82 which is open to the fuel inlet 46. In addition, the fuel rail 32 is fluidly connected by a passageway 84 to this annular fuel inlet chamber 82. This fuel passageway 84 may be formed in the injector cup 50 or be separate from the injector cup 50.
In operation, high pressure fuel flow from the fuel rail 32 flows through the passageway 84 and into the annular fuel inlet chamber 82. From the annular inlet chamber 82, the fuel flows through the injector inlet 46 and ultimately to its outlet 48 in the conventional fashion.
Any pressure pulsations that are contained within the fuel flow from the fuel rail 32 act equally on both O-rings 80 thus providing a longitudinal force on the fuel injector 28 in equal but opposite longitudinal directions. This, in turn, minimizes the downward force on the fuel injector 28 and thus the stress imposed on the clip plate 70 as well as vibrations imparted on the engine block 24.
With reference now to
The fuel reservoir 90 is rigid in construction and has an inside diameter preferably in the range of 1.2 d-1.5 d where d is the inside diameter of the fuel pipe 34. In practice, such sizing of the fuel reservoir 90 simply, but effectively, dampens and attenuates the fuel pump vibrations conveyed to the fuel rails 32.
Although the fuel reservoirs 90 are illustrated in
With reference now to
The reservoir 92 is also rigid in construction and is preferably cylindrical in shape. Furthermore, an inside diameter of the reservoir 92 is preferably in the range of 1.2 d-1.5 d where d equals the diameter of the fluid in the port 94 to the fluid reservoir 92.
With reference now to
From the foregoing, it can be seen that the present invention provides both a method and apparatus to effectively reduce and attenuate the transmission of pulsations and vibrations from the fuel pump in a direct injection internal combustion engine to the engine block.
Having described our invention, however, many modifications thereto will become apparent to those skilled in the art to which it pertains without deviation from the spirit of the invention as defined by the scope of the appended claims.
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|U.S. Classification||123/470, 123/456|
|International Classification||F02M61/14, F02M61/18|
|Cooperative Classification||F02M2200/09, F02M55/005, F02M61/14, F02M69/465, F02M55/025, F02M61/168, F02M2200/8023, F02M2200/40, F02M2200/856|
|European Classification||F02M55/00D2, F02M69/46B2, F02M61/16H, F02M55/02B, F02M61/14|
|Apr 2, 2007||AS||Assignment|
Owner name: HITACHI, LTD., JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:WATANABE, ATSUSHI;BADARINARAYAN, HARSHA;BORG, JONATHAN;AND OTHERS;REEL/FRAME:019100/0459;SIGNING DATES FROM 20070326 TO 20070402
|Oct 26, 2010||RF||Reissue application filed|
Effective date: 20100804
|Jan 4, 2012||FPAY||Fee payment|
Year of fee payment: 4